Calculating device



Filed Dec. 13, 1926 IIIIIII'IIIIIHIII-llf Vlllllllllillllllllll[willINVENTOR ATTORNEY Patented July s, 193.0

UNITED HARRY H. FERRIS, or Los ANGELES, CALIFORNIA GALCULATING DnvicnAppiieetien mea December- 1s,v 1926. serial' ne. 154,553.

the invention further includes the followingY novel features and detailsof construction, to

be hereinafter more fully described, illustrated in the accompanyingdrawings and pointed ont in the appended claim.

In the drawings Figure 1 isv an elevation of the invention applied foruse upon the. conventional form of square.

Figure 2 is a similar view of the calibrated clamping member.

Figure 3 is an end elevation thereof.

Figure 4 is an end elevation of an additional clamping member operableinconjunc tion with the remaining end of the calculating member.

Referring to the drawings in detail, wherein like characters ofreferencey denote corresponding parts, the reference character 10indicates the conventional form of builders or carpenters steel square.Slidably mounted upon the vertical leg'of the square is aclamping member11 including a set screw 12 extending within a slot 13 for engagementwith f said vertical leg. An enlarged portion 14 is carried upon theinner side edge of the clamping member and adjacent the lowermost cornerthereof and provided with a cut-out por-v tion 15, the lpurpose of whichwill be readily apparent.

A clamping member 16 ofa general configuration similar to that of theclamping member 11 is slidably mounted upon the horizontal leg of thesquare and adapted to be locked ina desired adjusted position after themanner of the clamping member 11.V An arcnate shaped scale 17 is carriedupon one side edge of the clamping member 16.` An enlargedportion 18carried by the upper left vhand corner of the clamping member 16 isprovided with an opening 19 whose side walls flare oppositely andoutwardly from a point substantially central of the opening.

" A calculating member consisting of an arm 20 marked olf in inches andtwelfths, to

be subsequently referred to as feet and inches,

has the 'upper end thereof pivot-ally mounted within the cnt-out portion15 of the enlarged portion 14 carried by the 'clamping member 11. Theremaining end of the calculating de vice is disposed through the opening19 and across the face of the'arcuate shaped scale 17. S'aid lscale iscalibrated to indicate vthe rise in inches per foot run.`

, 1f the run were 111/2 feet andthe rise 7l/2, the respective clampingmembers would be disposed in registration with the inch markings uponthe square. Said inch markings will now be considered as feet.vExtensions 21 carried by each of the .clamping members and ldisposedover the markings upon the square are divided into twelve divisions;each division representing one inch. l/Vhen the clamping members aredisposed in the man-y nerv as illustrated in Figure 1 of the drawing thelength of 'the comifnon rafter will be calculated upon'the arm 2Oimmediately behind the enlarge-d portion 18, the length Vbeing13feet'8inches. The distance between the pivot lpoint for the iarm and theexposed portion of the arm extending therefrom is Aequivalent tothevdistance from the center of the opening within which the set screw 22is threaded within the enlarged portion 18V to the rear edge of thelatter. rlfhe length of the common rafter will thus be indicated in feetbetween 13 and 14 and the portions of a e portion of the arm 2Oextending across thev arcuate shaped scale 17 willcorrectly indicate thepitch of the rafter in the same calculation. The diculty as generallyexperienced in the calculation of the length of rafters and pitchthereof has been the reduction 5 of inches ordinarily calculated 'insixteen sections to twelve. n the application of the present inventionthe inches are considered as feet and the sections of the feet areconsidered as twelfths. rEhe said tWelths are lo indicated upon theextensions 2l. A set screw 22 is carried by the enlarg-ed portion 18 ofthe clamping member 16 and adapted for biting engagement with theadjacent portion oil' the arm 2O to permit an operator to set l5 theinstrument While calculating the length oi" the raiter and pitch.

Squares of the character described are generally provided withcalculations upon the reverse sides thereof to give the pitch of a 20rafter in degrees, namely, an eight inch rise on twelve would bethree-fourths; the present invention overcomes the necessity ofreferring to the reverse side of the square which is often impossiblewhen the square lies Hush with a plate and rafter.

The invention is susceptible of various changes in its form, proportionsand minor details of construction, and the right is herein reserved tomake suoli changes as properly all Within the scope of the appendedclaim.

Having thus described the invention what is claimed is A raftermeasuring device adapted for use in conjunction with a square comprisingclamping members provided with slotted portions adapted to permitsliding movement upon the legs of the square, set screws carried by theclamping members and projecting vithinthe slotted portions and beingadapted o for engagement With the adjacent edges of the square legs toretain the clamping members in position for use, enlarged portionscarried upon each of the clamping members, said enlarged portions havingan opening therethrough Whose Walls are oppositely and outwardly flared,extensions carried by each of the clamping members having calibrationsadapted to cooperate with the calibrations upon the square, an armpivoted at one end o Within the single cut-out portion of one of theenlarged portions for sliding movement through the opening of theremaining enlarged portion and having graduations thereon, and one ofthe clamping members having Y d5 indicia thereon to cooperate with theadjacent edge of the arm to determine the pitch of a rafter Whose lengthis indicated upon the arm.

In testimony whereof I aiix my signature.

60 HARRY H. FERRrs.

